DESCRIPTION: (Applicant's Description) The broad long-term objective of this proposal is the minimally invasive destruction of cancerous tumors of the prostate. The specific aims of this proposal are to design, develop and evaluate a hand-held probe for Magnetic Resonance (MR) image-guided ablation of prostate cancer. Once the probe is fully functional, its use will improve the effectiveness of prostate cancer treatment by providing a non-invasive means for the in-situ destruction of selected lesions, with minimal collateral damage to the rest of the prostate. The proposed research will take place over a 36-month period and result in the design and construction of a trans-rectal probe capable of locating and destroying prostate tumors. The probe will incorporate an MR imaging coil for lesion identification and localization, MR tracking coils for probe localization, and a focused ultrasound transducer for the creation of therapeutic levels of heat at the focal spot. The MR tracking coils will be used to control the plane of MR image acquisition and be physically locked to the focal spot of the focused ultrasound transducer. Thus, images acquired with the probe will be automatically registered with the therapeutic focus of the device. MR imaging pulse sequences and analysis software will be developed to provide temperature-sensitive imaging of the probe's ultrasonic focal spot. The temperature-sensitive imaging protocols will be sensitive to sub-therapeutic levels of heat created by the transducer during location verification as well as therapeutic levels generated during the ablation of targeted tissue. The imaging and tracking functions of the probe will be validated in healthy volunteers. Work involving the delivery of focused ultrasound will be performed in cadaver models. The final system will be evaluated at a clinical site (to be determined) on a conventional 1.5T scanner and on an open 0.5T scanner designed for interventional use. If the probe proves successful in cadaver models, work in subsequent projects will focus on evaluation of the probe in a controlled population of clinical patients.